How to use the nikola.utils.write_metadata function in Nikola

def create_post(self, path, **kw):
        content = kw.pop('content', 'Write your post here.')
        one_file = kw.pop('onefile', False)  # NOQA
        is_page = kw.pop('is_page', False)  # NOQA
        metadata = OrderedDict()
        metadata.update(self.default_metadata)
        metadata.update(kw)
        makedirs(os.path.dirname(path))
        if not content.endswith('\n'):
            content += '\n'
        with codecs.open(path, "wb+", "utf8") as fd:
            if one_file:
                fd.write("////\n")
                fd.write(write_metadata(metadata))
                fd.write("////\n")
            fd.write(content)

def create_post(self, path, **kw):
        """Create a new post."""
        content = kw.pop('content', None)
        onefile = kw.pop('onefile', False)
        # is_page is not used by create_post as of now.
        kw.pop('is_page', False)
        metadata = {}
        metadata.update(self.default_metadata)
        metadata.update(kw)
        makedirs(os.path.dirname(path))
        if not content.endswith('\n'):
            content += '\n'
        with io.open(path, "w+", encoding="utf8") as fd:
            if onefile:
                fd.write(write_metadata(metadata, comment_wrap=False, site=self.site, compiler=self))
            fd.write(content)